This invention relates to piezoelectric ink jet modules.
A piezoelectric ink jet module includes a module body, a piezoelectric element, and an electrical connection element for driving the piezoelectric element. The module body, usually carbon or ceramic, is typically a thin, rectangular member into the surfaces of which are machined a series of ink reservoirs that serve as pumping chambers for ink. The piezoelectric element is disposed over the surface of the jet body to cover the pumping chambers and position the piezoelectric material in a manner to pressurize the ink in the pumping chambers to effect jetting.
In a typical shear mode piezoelectric ink jet module, a single, monolithic piezoelectric element covers the pumping chambers to provide not only the ink pressurizing function but also to seal the pumping chambers against ink leakage. The electrical connection is typically made by a flex print positioned over the exterior surface of the piezoelectric element and provided with electrical contacts at locations corresponding to the locations of the pumping chambers. An example of a piezoelectric shear mode ink jet head is described in U.S. Pat. No. 5,640,184, the entire contents of which is incorporated herein by reference.
In one known ink jet module, available from Brother, a resin diaphragm is provided next to each of the pumping chambers. The central region of each diaphragm is pumped by a piezoelectric feature. Electrodes are embedded in the piezoelectric material.